Starting with kernel 2.6, the kernel ntfs implementation underwent a complete re-write, and does now support limited ntfs writing capabilities. However, since ntfs-3G offers a much more complete solution, albeit in user-space and hence slightly slower, no-one seems to bother with the kernel driver anymore. Interestingly, the documentation for the kernel driver points towards (can't post links yet!) for more information. Following this link takes you to the Tuxera website!!!
I must admit that I'd never heard of Tuxera until Martin's reply above, and from the description, that would appear to be a good solution for hardware manufacturers, satisfying a requirement, whilst protecting themselves from legal issues! But I wonder why Humax don't mention ntfs compatibility in the user manual? Is it an oversight? Or is it not that reliable yet?
To find out what is really in there, we need to be able to shell into the Humax os, but that requires knowledge of (root?) usernames and passwords. Alternatively, since the os is open source, it *might* be possible to figure out what is going on from the source code, but if they are using Tuxera, that would be proprietary / closed source, and wouldn't show up. To get the source code, you need to e-mail Humax, and I haven't done enough posts yet to supply a link!
Interestingly, the list of open source software used includes xfsprogs (for the xfs filesystem). I wonder what they use that for? And why did they choose ext3 rather than the more recent ext4? Perhaps they are using ext3 for the root system, and xfs for media storage? Xfs originated in Irix, and is supposed to be very good with large files........